Ming, Pingjia (2014-06). Glow Discharge Enhanced Chemical Reaction: Application in Ammonia Synthesis and Hydrocarbon Gas Cleanup. Master's Thesis.
Thesis
Two different plasma enhanced processing technologies were investigated in this study: ammonia synthesis from steam and nitrogen, and hydrocarbon gas clean up. Ammonia is a common sanitizer in swimming pool and fish tank, changing the pH of the water, which does not benefit bacteria. Also ammonia is used in various NOx reduction technologies, for example, selective catalytic reduction (SCR) methods have been studied for the cleaning of diesel engine exhaust. A small compact glow discharge was applied to investigate ammonia synthesis from steam and nitrogen. Ammonia was successfully detected via UV-VIS absorbance and through increasing pH value of treated water by product gas. Heavier hydrocarbon C3 to C5 are produced with natural gas, but cannot be used in sensitive energy conversion systems, like solid oxide fuel cell (SOFC). Utilizing small amount of energy to clean up and reform heavier hydrocarbon into synthesis gas is necessary when using hydrocarbon sources which contain heavier hydrocarbons mixture such as EPE (74.8% methane, 8% ethane, 8% ethylene, 2.1% propane and 1.1% Propene). Non-thermal plasmas, due to their unique non-equilibrium characteristics, offer advantages as method of reforming at lower temperature (100-150 oC) and atmospheric pressure. For an EPE gas mixture, a high conversion and low specific energy cost is desirable. Variation in discharge power density, air and, water addition were tested, in order to find conditions which were energetically feasibility, efficiency and sufficiently reduced the higher hydrocarbon. High conversion efficiency was achieved, in propane and propene, which was more than 90%, without carbon deposition through air addition. For a 1 J/ml power density and 1.08 O2/C ratio condition, a process efficiency of 74% and 54% available output energy was achieved. At the same time, the concentration of ethane, ethylene, propane, propylene, and acetylene were cleaned-up to value of 1.01%, 1.67%, 0.08%, 0.00%, and 0.50%, respectively, less than 20% of their original input amount. Higher power density produced cleaner (less high hydrocarbons) in the products, and were still energetically feasible, but less efficient.
